Recent changes of fs-writeback cause such warnings if DETECT_HUNG_TASK is not enabled: INFO: The task sync:1342 has been waiting for writeback completion for more than 1 seconds. The reason is sysctl_hung_task_timeout_secs is 0 when DETECT_HUNG_TASK is not enabled, then it causes the warning message even if the writeback lasts for only one second. Guard the wakeup and logging with "#ifdef CONFIG_DETECT_HUNG_TASK" can eliminate the warning messages. But on the other hand, it is possible that sysctl_hung_task_timeout_secs be also 0 when DETECT_HUNG_TASK is enabled. So let's just check the value of sysctl_hung_task_timeout_secs to decide whether do wakeup and logging. Fixes: 1888635532fb ("writeback: Wake up waiting tasks when finishing the writeback of a chunk.") Fixes: d6e621590764 ("writeback: Add logging for slow writeback (exceeds sysctl_hung_task_timeout_secs)") Signed-off-by: Huacai Chen --- V2: Disable wakeup and logging for !DETECT_HUNG_TASK. V3: Also handle the case for DETECT_HUNG_TASK if sysctl_hung_task_timeout_secs is 0. fs/fs-writeback.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 5444fc706ac7..79b02ac66ac6 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -198,10 +198,11 @@ static void wb_queue_work(struct bdi_writeback *wb, static bool wb_wait_for_completion_cb(struct wb_completion *done) { + unsigned long timeout = sysctl_hung_task_timeout_secs; unsigned long waited_secs = (jiffies - done->wait_start) / HZ; done->progress_stamp = jiffies; - if (waited_secs > sysctl_hung_task_timeout_secs) + if (timeout && (waited_secs > timeout)) pr_info("INFO: The task %s:%d has been waiting for writeback " "completion for more than %lu seconds.", current->comm, current->pid, waited_secs); @@ -1944,6 +1945,7 @@ static long writeback_sb_inodes(struct super_block *sb, .range_end = LLONG_MAX, }; unsigned long start_time = jiffies; + unsigned long timeout = sysctl_hung_task_timeout_secs; long write_chunk; long total_wrote = 0; /* count both pages and inodes */ unsigned long dirtied_before = jiffies; @@ -2030,9 +2032,8 @@ static long writeback_sb_inodes(struct super_block *sb, __writeback_single_inode(inode, &wbc); /* Report progress to inform the hung task detector of the progress. */ - if (work->done && work->done->progress_stamp && - (jiffies - work->done->progress_stamp) > HZ * - sysctl_hung_task_timeout_secs / 2) + if (work->done && work->done->progress_stamp && timeout && + (jiffies - work->done->progress_stamp) > HZ * timeout / 2) wake_up_all(work->done->waitq); wbc_detach_inode(&wbc); -- 2.47.3